In recent years, there is proposed a package for mounting a light emitting device such as an LED (Light Emitting Diode) thereon (LED mounting package). For example, the LED mounting package may include a substrate having one surface formed with an LED connection pad (i.e. pad to be connected to a LED) and another surface formed with an external connection pad (i.e. pad to be connected to an external connection device) on another surface, and a through-wiring that connects the LED connection pad and the external connection pad (see, for example, International Publication Pamphlet No. WO 2004/084319).
However, the LED mounting package is required to form both the LED connection pad and the external connection pad on the one and the other surfaces of the substrate (e.g., ceramic substrate) after forming the through-wiring in a through-hole. Thus, a large number of processes is required for manufacturing the LED mounting package. This results in an increase of manufacturing cost of the LED mounting package.
As one method for reducing the manufacturing cost of the LED mounting package, the LED mounting package may be manufactured without forming an external connection pad on the other surface of the substrate and instead use a part of the through-wiring exposed from the other surface of the substrate as the external connection pad.
However, this method may lack a sufficient bonding strength because the through-wiring and the sidewall of the through-hole are not bonded to each other. As a result, a so-called “unsheathing” phenomenon may occur in which the LED connection pad and the through-wiring fall off from the substrate in a case where a pulling force is applied in a direction separating the LED connection from the substrate.